Switch indication circuits



oct. zo, 1942. A. l.. .lemma I 2,299,275

. SWITCH INDICATION CIRCUITS Filed Nov. a, 1941 Zj, `25r I mhw emme.

Patented Oct. 20, 1942 U NIT E D STATES 'ATENT OFF I CE 7- Claims.

My invention relates to railway signaling apparatus and particularly to improved means for indicating the position occupied by a track switch.

In application Serial No. 424,151 of Arthur E. Dodd, filed Dec. 23; 1941, there are shown several circuits for indicating the position of a track switch. Each of these circuits employs a polar indication relay and a biasedy neutral relay which are energized in series when the polar contacts of the switch control relay and of the indication relay are in correspondence', while a rectier is connected across the terminals of the neutral relay to prevent energzation of this relay by current of the incorrect polarity. The circuits of that application are also arranged so that when the polar contacts of the switch control relay and ofthe switch indication relay are out of correspondence, the circuit of the neutral relay is interrupted, while when the polarity of the energy supplied to the indication circuit is out of correspondence with the position of the polar contacts of the indication relay, a circuit including one of the rectiers is established to supply the indication relay with energy of the polarity effective to move the relay contacts to their other position.

It is an object of this invention to provide switch indication circuits of' the type described which are arranged so that when the contacts of the polar indication relay and of the polar switch control relay are out of correspondence,v

the circuit ofthe neutral relay is interrupted and a circuit independent of the rectiers is estab-l lished to energize the polar indication relay.

A further object of the invention is to provide improved switch indication circuits.

Other objects of the invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawing.

I shall describe three forms of switch indication circuits embodying my invention, and shall then point out the novel features thereof in claims.

In the drawing Fig. 1 is a diagram showing one form of switch indication circuit provided by my invention, and

Figs. 2 and 3 are diagrams showing modications which I may employ.

Similar reference characters refer to similar parts in each of the several views.

Referring to Fig. 1V of the drawing. there is shown therein a railway track switch W which is moved between its normal and reverse pcsitions -by a power operated switch machine SM. The switch machine SM may be of any appropriate construction well known in the art, while this machine is controlled by a polarized switch control relay WR. The circuit of the relay WR is governed by pole changing contacts I9. and II which may be controlled,v by a switch control lever L or other appropriate means.

` The switch W has associated therewith switch operated contacts I4 and I5 which are. governed in accordance with the position of the switch and control the supply of energy to indication wires I6 and I'I from which energy is supplied to relays WP and N.

'I'he relay WP is of the stick polarl type the contacts of which are moved to one position or the other depending on the polarity of the energy supplied to the relay winding, while on interruption ofthe supply of energy. to the relay winding the relay contacts remain in the position which they then occupy.

The auxiliary relay N is preferably of the polar biasedI type the contacts of which when released become picked up only when energy of a particular polarity is supplied' to theV relay winding. This relay is connected in the circuit so that its contacts pick up only when energy flows through the relay winding from the left-hand to the right-hand terminal thereof. Relays of the type which may be employed for this purpose are shown in Letters Patent of the United States No. 2,057,605 issued October 13, 1936, to Herman G. Blosser, and in application Serial No. 194,160 of Harry E. Ashworth.

The equipment is shown in the condition which it assumes when the control lever L and the switch W are in their normal positions.

AsA the lever L is in its normal position, con- I tacts I0 and' II cause energy of' normal polarity to be supplied' to the winding of switch control relay WR from a source the terminals of which are designated -land As` the relay WR is supplied with energy of normal polarity, its neutral contact 20 is picked up and its polar Contact' 2I occupies its left-hand or normal position so that a circuit is established to cause the switch machine SM to move the switch W to its normal position.

As the switch W is in its normal position, contact I5 establishes connection from the positive terminal of the sourceto wire I1 and contact I4 establishes connection from the negative terminal of the source to wire IS. Accordingly, the relays WP and N are energized in series over the circuit which is traced from the positive terminal of the source through contact I5, wire I'I, winding of relay WP, and normal polar contact 23 of relay WP to the left-hand terminal of the relay N, through the winding of the relay N, normal polar contact 24 of relay WR, wire I6, and contact I4 to the negative terminal of the source.

The energy supplied to relay WP is of the polarity effective to maintain its contact 23 in its normal position, while the energy supplied to the relay N is of the polarity effective to pick up the contacts of this relay. Accordingly, contact 25 of relay N is picked up and establishes a circuit which may be employed for any suitable purpose.

If it is desired to move the switch, the control lever L is moved to its reverse position so that contacts I il and II cause energy of reverse polarity to be supplied to relay WR with the result that contacts 2| and` 24 of the relay move to their right-hand or reverse positions. r

On movement of the contact 2| to its reverse position a circuit is established to cause the switch machine SM to move the switch W to its reverse position. i

On movement of contact 24 of relay WR to its reverse position the circuit traced above for energizing the relays -WP and N in series is interrupted with the result that contact 25 of relay N releases and interrupts the circuit controlled thereby. In addition, on this movement of the contact 24 of relay WR the relay WP is connected directly across the indication wires as wire I1 is connected to one terminal of the relay winding while the other terminal of this `winding is connected through normal polar contact 23 of relay WP and reverse polar contact 24 of relay WR to wire IS. As long as the switch remains in its normal position, the energy supplied to the winding of relay WP is of the polarity eiective to maintain the relay contact in its normal position.

When the switch moves to its reverse position, contact I5 establishes connection from the positive Yterminal of the source to wire I6 while contact I4 establishes connection from the negative terminal of the source to wire I1. As a result, there is reversal in the direction of flow of energy through the winding of reiay WP and the contact of this relay shifts to its right-*hand or reverse position so that the relays WP and N are again energized in series.

On movement of the contact 23 of relay P away rom its normal position the supply of energy to thewinding of the relay is interrupted, but the operating characteristics of the relay are such that the relay contact completes its movement to its reverse position.

The circuit for energizing relays WP and N with current of reverse polarity after movement of the contact of relay WP to its reverse position is traced from the positive terminal of the source through contact I5, wire I 6, and reverse polar contact 24 of relay WR to the left-hand terminal of the winding of relay N, through this winding, reverse polar contact 23 of relay WP, Winding of relay WP, wire I1, and contact I4 to the negative terminal of the source. The direction of ow of energy through the winding of relay N, therefore, is that which is effective to pick up the relay contacts, while the direction of flow of energy in the winding of relay WP is that which is elective to maintain the contact 23 in its reverse position so that-the relays WP and N continue to be energized in series. Accordingly, Contact 25 of relay N picks up and remains picked up as long as the switch remains in its reverse position.

On subsequent movement of the switch control lever L to its normal position so that energy of normal polarity is supplied to the relay WR the polar contacts of this relay shift to their normal positions and contact 2I establishes the circuit to cause the switch machine SM to move the switch to its normal position, while contact 24 interrupts the circuit traced above for energizing the relays WP and N in series and establishes a circuit to energize the relay WP directly from the wires I6 and II since at this time wire It is connected through normal polar contact 24 of relay WR and reverse polar contact 23 of relay WP to one terminal of the relay winding,

As a result of interruption of the circuit of relay N, its contact 25 releases and interrupts the circuit controlled thereby.

When the switch completes its movement to its normal position, contacts I4 and I5 change the energy supplied to wires I6 and II from reverse to normal polarity and the contact 23 of relay WP thereupon shifts to its normal position so that the relays WP and N are again energized in series while the energy supplied to relay N is of the polarity effective to cause the contact 25 to pick It will be seen, therefore, that when the polar contacts of relays WR and WP are in correspondence, the relays WP and N are energized in series, and when the polar contacts of relays WR and WP are out of correspondence, the circuit of the relay N is interrupted while the winding of the relay WP is connected directly across the indication wires.

As the circuit of the relay N is interrupted when the contacts of relays WR and WP are out of correspondence, this relay is deenergized as soon as an attemept is made vto move the switch and it remains deenergized until the switch completes its movement.

In addition it will be seen that when the energy supplied to the indication wires is of the polarity corresponding to the position of the polar contacts of the switch control relay, this energy is effective to cause the contacts of the relay WP to move into correspondence with the contacts of the switch control relay to thereby establish the circuit to energize the relays WP and N in series.

If at a time when the contacts of the relays WR and WP are in correspondence energy of the incorrect polarity is supplied to the indication wires, the windings of the relays WP and N will be energized in series. This energy should cause movement of the contact 23 of relay WP to its other position to thereby interrupt the circuit of relay N and to connect the relay WP directly across the indication wires. However, if the relay WP fails to respond to this energy and its contacts remain in correspondence with those of relay WR, the relay N will continue to be energized by this current of the wrong polarity. This energy will not pick up the contacts of relay N, but if the relay armature is moved to its pickedup position, this energy will be eiective to maintain it picked up.

While the possibility that the combination of conditions described above will occur is extremely remote, the possibility that the armature of the relair N will be maintained picked up under these conditions can be eliminated by connecting a rectifier K between the terminals of the relay Winding with the rectier poled to permit energy to flow from the right-handA to the left-hand terminal of the relay winding. Accordingly, if energy of the wrong polarity is supplied to the circuit of the relay N, it will be shunted through the rectier K and will` not energize the relay winding.

The modification shown' in Fig; 2 is similar to that shown in Fig. l but differs therefrom as' it employs two neutral relays, one of which indicates one position of the switch and the other of which indicates the other position of the switch. The neutral or auxiliary relays NA and NB are of the polar biased type and each is connected in the circuit so that its contacts pick up only when energy flows through the relay winding in the direction indicated by the arrow.

The equipment is shown in the condition which it assumes when the switch control relay contacts and the switch are in their normal positions. At this time the relays WP and NA are energized in series over the circuit whichis traced from the positive terminal of the source through contact I-5, wire Il, winding of relay WP, and normal polar contact 23 of relay WP to the right-hand terminal of the windingof relay NA, through this winding, normal polar contact 24 of relay WR, wire I6, and Contactr I4 to the negative terminal of the source. Accordingly, contact 25a of relay NA is picked up, while at this time the circuit of relay NB is interrupted so that the contact 25h of this relay is released.

If it is desired to reversethe switch, the control lever L is moved to its reverse position to change the polarity of the energy supplied to the relay WR and the polar contacts of this relay shift to their reverse position and contact 2.! establishes a circuit to cause the switch. machine S-M to move the switch W to its reverse position, while contact 24 interrupts the circuit traced above for energizing the relays WP and NA in series and establishes a circuit to connect the relay WP directly across'the indication wires. The circuit for energizing therelay WP' is traced from the wires Vl: through theA relay winding,

normal polar Contact 2l of the relay WP, and

reverse polar contact 24" of relay WR to wire IS, while the energy supplied to the relay WP is effective to maintain the' relay contacts in their normal positions.

When the-switch completes its movement to its reverse positiony energyof reverse polarity is supplied to relay WP' over thev circuit just traced.v and this energy causes the relay contacts to shift to their reverse position with the result that contact 21 interrupts the circuit for connecting relay .f

WP across the indication wires and contact. 23 establishes a circuit to energize the relays. WP and NB in series. This circuit is traced from the positive terminal ofthe source through contact I5, wire l5, and reverse contactV 2liz of relay W'R to the left-hand terminal of the winding of relay NB, through this winding, reverse polar contact 23 of relay W-P, winding of relay WP, wire Il, and contact I4 to the negative terminal. This energy is effective tomaintain the contacts of relay WP in their reverse positions while it' is also eiective to pick up the contacts 25D of relay NB. Accordingly, contact 25h of relay NB' picks up and establishes a circuit to indicate that the switch is in its reverse position.

When it is desired to return the switch to its normal position, the control lever L is moved to its normal position to cause contacts I9 and: H to establish circuits to supply energy of normal polarity to the relay WR and the polar contacts of. this relay-` shift to their normal positions/with the result that contact 2| establishes the circuit to cause the switch machine to move the switch to its normal.v posi-tion; On this: movement of the contacts of: relay WR contact 24 interrupts the circuit traced above forl energizing the relays WP and NB in series and establishes a circuit to connect the relay WPl directly across the indicationl wires.. At this-time, with thel contacts of relay WP in their reverse positionsI and the contacts of relay WR in their normal positions, indication wi're IE'I is connected to one terminal of the winding of relay WP while indication wire I'S is connected through' normal polar contact 24 of relayfWR-and reversepolar contact 21 of relay WP'to the other terminal. of therelay winding.

Accordingly, when. the' switch completes its movement toy its normal position. andcontacts I4 and I'5 cause energy of normal polarity to be supplied to the indication wires" t6? and IT, the relay WP is energized. with current effective to move the relay contacts to their normal" position. On this movement of the contacts of relay WP contact 21v interrupts the circuit just traced for connecting relay` WP directly across the indication` wires whil'esccntact 23 establishes the circuit previously traced for energizing thev relays WP and: NA in series. The energy supplied to these relays is eiective to maintain the contacts of relay WP in' their.' normal positions, and is effective to pick up the contacts of relay NA.

From the foregoingiit' will be seen that this modification is arranged so that when the polar contacts of theswitcli control relay WR and of the switch indication relay WP are in correspondence, the' relay WP is energized from the indication wires in series with one or the other ofthe neutralv relays, the one depending on the position of the polar contacts of the relays WP and WR. f

In addition it will be seen that when the polar contacts of the relaysy WR and WP are out of correspondence, the circuits of' relays NA and NB are interrupted, while the relay WP is connected directly across the indication wires so that on a change in the polarity of the energy supplied to the indication wires thecontacts of the rel'ay WP` will.' move into correspondence with those. of the relay WR andV establish a circuit to energize the relay WP in series with one of the neutralA relays.

Accordingly, as soon as' an attempt is' made to move the switch, the circuit of one of the auxiliary relays isinterrupted, while the circuit of the other auxiliary relays isY not estab'- lished until'. the switch completes itsv movement so that thepolarity of" the energy supplied to the indication wires is changed and the contacts of the relay WP move into correspondence with those of relay WRL.

As explained: in connection with Fig. l,` ifenergy' of the wrong polarity is supplied tothe indication wires at a time when the contacts of the relays WP andv WR. are in correspondence, energy may flow through the winding of one ofthe auxiliary relays in the wrong direction t'o pick up the relay contacts, but this energy would` be eifective'to hold thel relay contacts picked upifthe relay armature" were moved to its pickedup' positionf. In order toi eliminate this possibility of improper energization of the neutral relays eacl'iof these relays has a rectifier K connected acrossits.' terminals and poled to' per mit. energy to' fl'ow therethrough in the directionopposite' to that which will pick up the relay contacts.

The modification shown in Fig. 3 is similar to that shown in Fig. 2 but differs therefrom as it employs two polar contacts on the relay WR and one on the relay WP, instead of two on WP and one on WR.

When the polar contacts of the relays WR and WP are in their normal positions and the switch is in its normal position, the relays WP and NA are energized in series over the circuit which is traced from the positive terminal of the source through switch operated contact I5, wire l'i, winding of relay WP, normal polar contact 23 of relay WP, winding of relay NA, normal polar contact 24 of relay WR, wire l5, and contact I4 to the negative terminal Aof the source. Accordingly, contact 23 of relay WP is maintained in its normal position while contact 25a of relay NA is picked up.

On movement of the contacts of relay WR to their normal position contact 24 interrupts the circuit traced above for energizing relays NVP and NA in series, while contact 23 of relay WR establishes a circuit to connect relay 'WT directly across the indication wires. At this time wire l5 is connected through reverse polar contact 28 of relay WR and normal polar contact 23 of relay WP to a terminal of the winding of relay WP. Accordingly, on reversal of the pol-arity of the energy supplied to the indication wires the contacts of relay WP shift to their reverse position and contact 23 interrupts the circuit forf'connecting the relay WP directly across the indication wires and establishes a circuit to energize the relays WP and NB in series.

The circuit for energizing the relays WP and NB in series is traced from the positive terminal of the source through contact l5, wire Iii, reverse polarcontact 24 of relay WR, winding of relay NB, reverse polar contact 23 of relay WP, winding of relay WP, wire I1, and contact I4 to the negative terminal of the source. The energy supplied to these relays at this time is effective to maintain the contacts of the relay XP in their reverse position and to pick up contact 25h 0f relay NB.

If it is now desired to return the switch to the s normal position, energy of normal polarity is supplied to the relay WR and its contacts move to their normal positions and contact 24 of relay WR interrupts the circuit traced above for energizing the relays WP and NB in series, while contact 28 of relay WR establishes a circuit to connect relay WP directly -across the indication wires. At this time wire i 6 is connected through normal polar contact 28 of relay WR and reverse polar contact 23 of relay WP to one terminal of the winding of relay WP.

When the switch completes its movement to its normal position, energy of normal polarity is supplied to the indication wires and this energy causes the contacts of relay WP to shift to their normal positions so that contact 23 interrupts the circuit just traced fo1` connecting the winding of relay WP directly across the indication wires and establishes the circuit including normal polar contact 2li of relay WR for energizing the relays WP and NA in series.

It will be seen, therefore, that this modification, like that shown in Fig. 2, operates so that when the contacts of relays WR and WP are in correspondence, the relay WP is energized in series with one or the other of the neutral relays, and when the contacts of the relays WP and WR are out of correspondence, the circuits of the neutral relays NA and NB are interrupted while the winding of the relay WP is connected directly across the indication wires so that this relay will be energized and its contacts will move into correspondence with those of relay WR.

Although I have herein shown and described only three forms of switch indication circuits embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a track switch, a switch machine for moving said switch between a normal and a reverse position, a polarized switch control relay to which energy of normal polarity is supplied at times and to which energy of reverse polarity is supplied at other times, said relay being effective when its polar contacts are in their normal positions to cause the switch machine to move the switch to its normal position and being effective when its polar contacts are in their reverse positions to cause the switch machine to move the switch to its reverse position, an indication circuit comprising a pair of indication wires, means eiective according as the switch is in its normal or reverse position to supply to said indication circuit energy of normal or reverse polarity, a polar indication relay having its winding connected in series with one of said indication wires, an auxiliary relay, a polar contact of said indication relay being effective when in its normal position to connect one of said indication wires to one terminal of the winding of said auxiliary relay, a polar contact of said switch control relay being effective when in its normal position to connect the other of said indication wires to the other terminal of the winding of said auxiliary relay to thereby energize the polar indication relay and said auxiliary relay in series from said indication wires, means including a polar Contact of each of said polarized relays and eiective when said contacts are out of correspondence to energize said polar indication relay from said indication wires independently of said auxiliary relay, and a circuit controlled by a contact of said auxiliary relay.

2. In combination, a track switch, a switch machine for moving said switch between a normal and a reverse position, a polarized switch control relay to which energy of normal polarity is supplied at times and to which energy of reverse polarity is supplied at other times, said relay being eiective when its polar contacts are in their normal positions to cause the switch machine to move the switch to its normal position and being effective when its polar contacts are in their reverse positions to cause the switch machine to move the switch to its reverse position, an indication circuit comprising a rst and a second indication wire, means eiective according as the switch is in its normal or its reverse position to supply to said indication circuit energy of normal or reverse polarity, a polar indication relay having one terminal of its winding connected to the i'lrst indication wire, an auxiliary relay, a polar contact of said indication relay being effective when in its normal position to connect the other terminal of said indication relay winding to one terminal of the winding of the auxiliary relay, a polar contact of said switch control relay being eiective when in its normal position to connect the second indication wire -to the other terminal of the winding of said auxiliary relay, means including a reverse polar contact of 'the switch control relay and a normal polar contact of the indication relay for connecting the second indication wire to the other terminal of the winding of said indication relay, Ameans including a normal polar contact of the switch control relay and a reverse polar contact of the indication relay for also connecting the second indication wire to the other terminal of the winding of said indication relay, and a circuit controlled by a contact of said auxiliary relay.

3. In combination, a track switch, a 4switch machine for moving said switch between a normal and a reverse position, a polarized switch control relay to which energy of normal polarity is supplied at times and to which energy of reverse vpolarity is supplied at vother times, said relay being effective -when its polar 4contacts are in their normal positions to cause the switch machine to move the switch lto its normal position and being effective when its polar .contacts are in their reverse positions to cause the switch machine to more the switch to its reverse position, an indication circuit comprising a rst and a second indication wire, means eiiective according as the :switch is in its normal or its reverse position to f supply to said indication circuit energy of normal or reverse polarity, a polar indication relay having one terminal of its winding connected to the first indication wire, an auxiliary relay having a winding having a iirst and a second terminal, a polar contact of said indication relay being effective according as it is in its normal or reverse position to connect the other -terminal of the indication relay winding to the rst or the second terminal of the auxiliary relay winding, a polar contact of said switch control relay being effective according as it is in its normal or reverse position to connect said second indication wire to the second or the first terminal of said auxiliary relay winding, and a circuit controlled by a contact of said auxiliary relay.

4. In combination, a track switch, a switch machine for moving said switch between a normal and a reverse position, a polarized switch control relay to which energy of normal polarity is supplied at times and to which energy of reverse polarity is supplied at other times, said relay being effective when its polar contacts are in their normal positions to cause the switch machine to move the switch to its normal position and being effective when its polar contacts are in their reverse positions to cause the switch machine to move the switch to its reverse position, an indication circuit comprising a rst and a second indication wire, means effective according as the switch is in its normal or its reverse position to supply to said indication circuit energy of normaly or reverse polarity, a polar indication relay having one terminal of its winding connected to the first indication wire, a rst and a second auxiliary relay, a polar-contact of said indication relay being effective when in its normal position to connect the other terminal of the indication relay winding'to one terminal of the winding of the first auxiliary relay and being effective when in its reverse position to connect said other terminal of the indication relay winding to one terminal of the second auxiliary relay winding, a polar contact of said control relay being eiective when in its normal position to connect the second indication wire to the other terminal ofthe lwinding of the rst auxiliary relay and being effective when in its re- Verse position to connect the second indication wire to the other terminal o f the winding of the second auxiliary relay, means including a norm-al polar contact of said control relay and a reverse -polar contact of said indication relay for connecting theisecondgindication wire to the other terminal of the winding of the indication relay, means including a reverse polar contact of said control relay and a normal polar contact of said indication relay foralso connecting the second indication wire to the other terminal of the winding of the indication relay, a circuit controlled by a contact of the iirst auxiliary relay, and a circuit controlled by a contact of the second auxiliary relay.

5. In combination, a track switch, a switch machine for Vmoving said switch between a Vnormal and a reverse position, a polarized switch control relay towhich energy of normal polarity is supplied vat times and to vwhich energy of reverse polarity is supplied at other times, saidrelay being effective when its polar contacts are in their normal positions to cause the switch machine -to move the switch to its normal position and being effective when its polar contacts `are in `their reverse positions to cause the switch machine to move the switch to its reverse position, an indication circuit comprising a rst and a second indication wire, means effective according as the switch is in its normal or its reverse position to supply to said indication circuit energy of normal or reverse polarity, a polar indication relay having one terminal of its winding connected to the rst indication wire, an auxiliary relay, means including a normal polar contact of the control relay and a normal polar ,contact of said indication relay for connecting the second indication Wire to the other terminal of the winding of the indication relay in series with the winding of the auxiliary relay, means including a reverse polar contact of the control relay and a normal polar contact of the indication relay for connecting the second indication wire to the other terminal of the winding of the indication relay independently of the auxiliary relay winding, means including a normal polar contact of the control relay and a reverse polar contact of the indication relay for also connecting the second indication wire to the other terminal of the winding of the indication relay independently of the winding of the auxiliary relay, and a circuit governed by a contact of said auxiliary relay.

6. In combination, a track switch, a switch machine for moving said switch between a normal and a reverse position, a polarized switch control relay to which energy of normal polarity is supplied at times and to which energy of reverse polarity is supplied at other times, said relay being effective when its polar contacts are in their normal positions to cause the switch machine to move the switch to its normal position and being effective when its polar contacts are in their reverse positions to cause the switch machine to move the switch to its reverse position, an indication circuit comprising a first and a second indication wire, means effective according as the switch is in its normal or its reverse position toV supply to said indication circuit energy of normal or reverse polarity, a polar indication relay having one terminal of its winding connected to the first indication wire, a rst and a second auxiliary relay, means including a normal polar contact of the control relay and a normal polar contact of the indication relay for connecting thesecond in-` dication wire to the other terminal o f the winding of the indication relay inlseries with the winding of the rst auxiliary relay, means including a reverse polar contact of the control relay and a reverse polar contact of the indication relay for connecting the second indication wire to the other terminal of the indication relay in series with the winding of the second auxiliary relay, means including a reverse polar contact of the control relay and a normal polar contact of the indication relay for connecting the second indication wire to the other terminal of the winding of the indication relay independently of the winding of either auxiliary relay, means including a normal polar contact of the control relay and a reverse polar contact of the indication relay for also connecting the second indication wire to the other terminal of the winding oi the indication relay independently of the winding of either auxiliary relay, a circuit controlled by a contact of the rst auxiliary relay, and a circuit controlled by a contact of the second auxiliary relay.

7. In combination, Ya track switch, a switch .machine for moving said switch between a norlli reverse polarity is supplied 4at other times, said relay being effective when its polar contacts are in their normal positions to cause the switch machine to move the switch to its normal position and being eiective when its polar contacts are in their reverse positions to cause the switch machine to move the switch to its reverse position, an indication circuit comprising a first and a second indication wire, means effective according as the switch is in its normal or its reverse position to supply to said indication circuit energy of normal or reverse polarity, a polar indication relay having one terminal of its winding connected to the rst indication wire, an auxiliary relay, means including a normal polar contact of the control relay and a normal polar contact of the indication relay for connecting the second indication wire to the other terminal oi the winding of the indication relay in series with the winding of said auxiliary relay, means independent of the winding of said auxiliary relay and including a polar contact of each of said polar relays for connecting the second indication wire to the other terminal of the winding of the indication relay when said polar contacts are out of correspondence, and a circuit controlled by a contact of said auxiliary relay.

ARTHUR L. JEROME. 

